How to use logs to debug Golang functions?

Use logs to debug Golang functions: Use the log package to add logging. Specify the logging level, such as Info(), Debug(), or Error(). Print log messages in your code to understand the status and behavior of functions. Use best practices, such as using defer log.Flush() and avoiding outputting sensitive data.

Debugging Golang functions using logs

Logging is a powerful tool for debugging Go functions, it allows printing meaningful messages to Understand the state and behavior of the program.

Add logging to your code

Easily add logging to your code using the log package:

import (
  "context"
  "fmt"
  "io"
  "log"
)

func myFunction(ctx context.Context, w io.Writer) {
  log.SetOutput(w)
  log.Println("Hello from myFunction!")
}

Configure logging level

You can specify the logging level, such as Info(), Debug(), Error( ):

import (
  "context"
  "fmt"
  "io"
  "log"
)

func myFunction(ctx context.Context, w io.Writer) {
  log.SetOutput(w)
  log.Printf("[DEBUG] Hello from myFunction!")
}

Practical case

Consider a simple function that calculates the sum of two numbers:

func add(a, b int) int {
  return a + b
}

To debug this function, you can add a log message before calling it:

import (
  "fmt"
  "log"
)

func main() {
  log.Println("Calling add(1, 2)")
  fmt.Println(add(1, 2))
}

This will print the following:

Calling add(1, 2)
3

This is easy to understand and provides a clear debugging message.

Best Practices

• Use defer log.Flush() to ensure that all log messages are written.
• Avoid outputting sensitive data in log messages.
• Consider using a logging framework such as logur to simplify logging and log level management.

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